Cu-BTC Metal Organic Framework Research Articles

A novel electrochemical sensor based on CuBTC metal–organic framework decorated with carbon nanotube for highly sensitive detection of enrofloxacin in water samples

A novel electrochemical sensor based on CuBTC metal–organic framework decorated with carbon nanotube for highly sensitive detection of enrofloxacin in water samples

Investigation of Bimetallic silver-copper BTC MOF for electrochemical CO2 reduction in Zero-gap Membrane electrode assembly (MEA) configuration

Bimetallic Metal-Organic Frameworks (MOFs) of silver, copper and the ligand benzene 1,3,5-tricarboxylate (AgCu-BTC MOFs), derived from Cu-BTC (HKUST-1), have been synthesized by fast co-precipitation method and investigated for CO2 reduction reaction (CO2RR). Three AgCu-BTC MOF variants were synthesized with varying Ag content: AgCu-1 (9.4 at.%), AgCu-2 (12.5 at.%), and AgCu-3 (16.5 at.%). A range of structural characterization techniques, including SEM-EDS, XRD, FTIR, and XPS, were utilized, revealing the formation of low-crystalline AgCu-BTC MOF with Ag+1 in an ionic state coordinated to the BTC framework. The investigation focused on CO2 reduction using humidified CO2 gas with bimetallic AgCu MOFs as electrocatalysts in a zero-gap MEA setup. The setup included a gas diffusion electrode (GDE) with a Sustainion Anion exchange membrane and bicarbonate as the anolyte. Cyclic Voltammetry (CV) and Linear Sweep Voltammetry (LSV) showed that the AgCu-3 MOF, with the highest silver content (16.5 at.%), exhibited a lower onset potential at -0.65 V vs Ag/AgCl compared to pristine Cu-BTC MOF owing to the better activity with Ag inclusion. Constant potential (CP) experiments combined with product analysis indicated that AgCu-3 MOF predominantly produced CO and H2 as the main products, achieving a faradaic efficiency of approximately 60% for CO production and 5% for hydrogen production. Moreover, reducing the humidity level in the inlet CO2 gas stream from 80% to 20% RH increased CO production by 2-fold, simultaneously suppressing the HER. This reduction in humidity resulted in an increased local concentration of CO2 at the catalyst site, leading to an enhanced CO2RR rate. SEM and FTIR investigations after the CP experiment demonstrated the instability of the AgCu-3 MOF, revealing substantial morphological changes under humid CO2 conditions.

Impact of copper and cobalt-based metal-organic framework materials on the performance and stability of hole-transfer layer (HTL)-free perovskite solar cells and carbon-based

This article investigates the impact of metal-organic frameworks (MOFs) on the performance and stability of perovskite solar cells (PSCs), specifically focusing on the type of metal and the morphology of the MOF. Two types of MOFs, copper-benzene-1,3,5-tricarboxylate (Cu-BTC MOF) with spherical morphology and cobalt-benzene-1,3,5-tricarboxylate (Co-BTC MOF) with rod morphology, are synthesized and spin-coated on TiO2 substrates to form FTO/TiO2/MOF/CH3NH3PbI3/C-paste PSCs. The morphology and size of the MOFs are characterized by scanning electron microscopy (SEM), and the crystallinity and residual PbI2 of the perovskite films are analyzed by X-ray diffraction (XRD). The results show that the Co-BTC MOF PSC exhibits the highest power conversion efficiency (PCE) of 10.4% and the best stability, retaining 82% of its initial PCE after 264 h of storage in ambient air. The improved performance and stability are attributed to the enhanced crystallinity and reduced residual PbI2 of the perovskite film after Co-BTC MOF modification. The paper showcases the immense potential of MOF-based interlayers to revolutionize PSC technology, offering a path toward next-generation solar cells with enhanced performance and longevity.

Two-step extraction for the evaluation of metal-organic framework impregnated materials.

Metal-organic frameworks (MOFs) are widely used for gas adsorption, separation, and sensing materials. In most cases, MOFs are not used in their crystal form but as impregnated materials because the fine crystals result in high-pressure drops. One key characteristic of MOF-impregnated materials is the amount of MOF in the material. This is evaluated using the wet digestion method; however, it is limited to determining only the metal content. Moreover, some metal, denoted as free metal, will not react with ligands to form MOFs. Additionally, it is crucial to determine the ligand amount, which cannot be determined using wet digestion. In the present study, a two-step extraction method for copper (II) benzene-1,3,5-tricarboxylate (Cu-BTC MOF) impregnated materials was developed to determine the MOF formed and free metals and ligands. Various solvents were applied to evaluate the extraction efficiencies. The results led to the selection of ethanol (EtOH) for extracting free Cu2+ and BTC, while 0.3M HNO3 was chosen to extract MOF-formed Cu2+ and BTC. The MOF-impregnated sample material was first extracted using EtOH and then 0.3M HNO3. The Cu2+ and BTC in the obtained extract solutions, as well as EtOH and HNO3, were analyzed using flame atomic absorption spectroscopy and high-performance liquid chromatography, respectively. In standard addition tests, free and MOF-formed Cu2+ and BTC were quantitatively extracted from MOF-impregnated materials. The developed two-step analysis method was successfully applied to Cu-BTC-impregnated materials used in gas sensing.

Copper(II) Ions Originating from CuBTC MOF Act as a Soluble Catalyst in the Friedländer Synthesis.

The copper-based metal-organic framework (MOF), CuBTC (where H3BTC = benzene-1,3,5-tricarboxylate), has been reported as a reusable heterogeneous catalyst for the Friedländer synthesis of substituted quinolines, which are desirable targets in the pharmaceutical industry. Because of this application, we further investigated the CuBTC-catalyzed Friedländer synthesis of 3-acetyl-2-methyl-4-phenylquinoline. CuBTC was synthesized in-house and used as a catalyst for the Friedländer synthesis. Fresh and used CuBTC were analyzed using scanning electron microscopy (SEM), powder X-ray diffraction (pXRD), and X-ray photoelectron spectroscopy (XPS). The used CuBTC shows structural breakdown in pXRD patterns and SEM images. Despite the structural breakdown, the desired product, 3-acetyl-2-methyl-4-phenylquinoline, is still produced in a moderate yield (76.3% ± 0.2), as confirmed via time-of-flight mass spectrometry and nuclear magnetic resonance spectroscopy. Inductively coupled plasma atomic emission spectroscopy of the recovered supernatant solution indicates the presence of copper(II) ions in solution. Thus, we hypothesized that the standard Friedländer conditions may degrade the CuBTC framework, resulting in copper(II) ions in solution. Control experiments with copper(II) from Cu(NO3)2·3H2O catalyzes the Friedländer reaction in yields (75.6% ± 0.1) equal to that of the CuBTC MOF. Overall, our findings suggest that CuBTC acts as a copper(II) source, and the copper(II) ions originating from the CuBTC MOF are responsible for the observed catalysis.

Trailblazing Kr/Xe Separation: The Birth of the First Kr-Selective Material.

Efficient separation of Kr from Kr/Xe mixtures is pivotal in nuclear waste management and dark matter research. Thus far, scientists have encountered a formidable challenge: the absence of a material with the ability to selectively adsorb Kr over Xe at room temperature. This study presents a groundbreaking transformation of the renowned metal-organic framework (MOF) CuBTC, previously acknowledged for its Xe adsorption affinity, into an unparalleled Kr-selective adsorbent. This achievement stems from an innovative densification approach involving systematic compression of the MOF, where the crystal size, interparticle interaction, defects, and evacuation conditions are synergistically modulated. The resultant densified CuBTC phase exhibits exceptional mechanical resilience, radiation tolerance, and notably an unprecedented selectivity for Kr over Xe at room temperature. Simulation and experimental kinetic diffusion studies confirm reduced gas diffusion in the densified MOF, attributed to its small pore window and minimal interparticle voids. The lighter Kr element demonstrates facile surface passage and higher diffusivity within the material, while the heavier Xe encounters increased difficulty entering the material and lower diffusivity. This Kr-selective MOF not only represents a significant breakthrough in Kr separation but also demonstrates remarkable processability and scalability to kilogram levels. The findings presented herein underscore the transformative potential of engineered MOFs in addressing complex challenges, heralding a new era of Kr separation technologies.

Metal-organic framework Cu-BTC for overall water splitting: A density functional theory study

Metal-organic framework Cu-BTC for overall water splitting: A density functional theory study

Ru-Doped Ultrasmall Cu Nanoparticles Decorated with Carbon for Electroreduction of Nitrate to Ammonia.

Electrocatalytic nitrate reduction reaction offers a sustainable approach to treating wastewater and synthesizing high-value ammonia under ambient conditions. However, electrocatalysts with low faradaic efficiency and selectivity severely hinder the development of nitrate-to-ammonia conversion. Herein, Ru-doped ultrasmall copper nanoparticles loaded on a carbon substrate (Cu-Ru@C) were fabricated by the pyrolysis of Cu-BTC metal-organic frameworks (MOFs). The Cu-Ru@C-0.5 catalyst exhibits a high faradaic efficiency (FE) of 90.4% at -0.6 V (vs RHE) and an ammonia yield rate of 1700.36 μg h-1mgcat.-1 at -0.9 V (vs RHE). Moreover, the nitrate conversion rate is almost 100% over varied pHs (including acid, neutral, and alkaline electrolytes) and different nitrate concentrations. The remarkable performance is attributed to the synergistic effect between Cu and Ru and the excellent conductivity of the carbon substrate. This work will open an exciting avenue to exploring MOF derivatives for ambient ammonia synthesis via selective electrocatalytic nitrate reduction.

Detection of Ammonium Ion by An Electrochemical Sensor Based on Cu-BTC

There is a growing interest in utilizing metal-organic frameworks (MOFs) for the development of electrochemical sensors with superior performance. In this work, a study on the detection of ammonium ion (NH4 +) on metal-organic frameworks (MOFs) Cu-BTC surface has been conducted by using both experimental and computational methods. By using DFT calculation, the adsorption energy of ammonium ion (NH4 +) on the MOF surfaces was determined. The calculation result showed that NH4 + molecules can be adsorbed on the surface of Cu-BTC with an adsorption energy value of -1.51 eV. Additionally, we performed the synthesis of Cu-BTC and, using CV (Cyclic Voltammetry), we obtained a working area of around -0.113 V. Furthermore, chronoamperometry tests revealed that the addition of ammonium at concentrations of 0.05, 0.1, and 0.15 mM resulted in changes in the current. The sensor also showed good stability and an increase in peak current at each tested concentration. This confirms that the MOFs tested can be utilized as ammonium ion sensors.

The adsorption of direct red 23 as a toxic pollutant in aqueous solution by using surface modified metal-organic framework containing tricarboxylic acid benzene ligand

In this research, Cu-BTC (C-BTC) metal-organic framework (MOF) was prepared and characterized. The synthesized C-BTC was modified with 3-aminopropyltrimethoxysilane to synthesize C-BTC-NH2. The ability to remove the direct red 23 (DR-23) dye by the synthesized materials (C-BTC and C-BTC-NH2) as adsorbents was investigated. The effect of operational parameters on dye removal was investigated. The results showed that the ability of the modified adsorbent (C-BTC-NH2) to adsorbed dye is more than the raw adsorbent (C-BTC). The amount of dye adsorption is high in acidic pH values. Increasing the amount of adsorbent and decreasing the pH of solution causes an increase in the percentage of dye adsorption and enhance in the DR-23 concentration causes a decrease in the percentage of DR-23 removal. The results of dye adsorption were matched with different isotherms and removal process followed the Langmuir isotherm. The experimental data exhibited a good fit with the Langmuir isotherm model (R2 = 0.9637), with the maximum adsorption capacity (Q0) of the calculated as 89.2857 and 2500 mg/g for DR-23 removal by C-BTC and C-BTC-NH2, respectively. Dye adsorption follows pseudo-second-order kinetics and k2 is PSO rate constant 0.0028 and 0.010 for by C-BTC and C-BTC-NH2, respectively. The data presented that C-BTC-NH2 as a modified adsorbent has high removal ability and is appropriate adsorbent for dye adsorption from aqueous solution.

Antibacterial efficacy of copper-based metal-organic frameworks against Escherichia coli and Lactobacillus.

The widespread and excessive use of antimicrobial drugs has resulted in a concerning rise in bacterial resistance, leading to a risk of untreatable infections. The aim of this study was to formulate a robust and efficient antibacterial treatment to address this challenge. Previous work focused on the effectiveness of the Cu-BTC metal-organic framework (MOF; BTC stands for 1,3,5-benzenetricarboxylate) in combatting various bacterial strains. Herein, we compare the antibacterial properties of Cu-BTC with our newly designed Cu-GA MOF, consisting of copper ions bridged by deprotonated gallate ligands (H2gal2-), against Escherichia coli (E. coli) and Lactobacillus bacteria. Cu-GA was synthesized hydrothermally from copper salt and naturally derived gallic acid (H4gal) and characterized for antibacterial evaluation. The gradual breakdown of Cu(H2gal) resulted in a significant antibacterial effect that is due to the release of copper ions and gallate ligands from the framework. Both copper MOFs were nontoxic to bacteria at low concentrations and growth was completely inhibited at high concentrations when treated with Cu-BTC (1500 μg for E. coli and 1700 μg for Lactobacillus) and Cu-GA (2000 μg for both bacterial strains). Furthermore, our agarose gel electrophoresis results indicate that both MOFs could disrupt bacterial cell membranes, hindering the synthesis of DNA. These findings confirm the antibacterial properties of Cu-BTC and the successful internalization of Cu2+ ions and gallic acid by bacteria from the Cu-GA MOF framework, suggesting the potential for a sustained and effective therapeutic approach against pathogenic microorganisms.

Flexible hierarchical polypyrrole-coated Cu-BTC MOFs photothermal textile for efficiently solar water evaporation and wastewater purification

Solar-driven interfacial water evaporation (SDIWE) endures a significant potential for producing clean water from seawater and wastewater because it requires no additional energy source. Photothermal materials with efficient solar absorption and pollutant removal capabilities are critical for SDIWE. However, an efficient and facile strategy to prepare a high-performance and flexible photothermal material and simultaneously prevent the salt accumulation for efficient and long-term steady evaporation to produce potable water from seawater and wastewater is still a challenge. Herein, based on the MS and ALD processes, two novel flexible photothermal materials are synthesized using the flexible polyester fabric substrate, hierarchical metal–organic framework Cu-BTC MOFs, and polypyrrole (PPy) as a light-absorption layer. In particular, under the synergistic effect of the hierarchical porous Cu-BTC MOFs and PPy with excellent solar absorption, the flexible photothermal material possesses excellent light absorption (92.58 % ∼ 93.98 %), super hydrophilicity, low thermal conductivity, high evaporation rate (1.53 ∼ 1.56 kg m-2h−1 for 15 days), outstanding salt resistance (1.42 kg m-2h−1 at a salinity of 15 wt%), and excellent metal ions and organic pollutants removal capacity after solar evaporation. These multifunctional properties ensure its great application prospect for future freshwater production while also providing a new reference for other applications.

Recent advances of Copper- BTC metal-organic frameworks for efficient degradation of organic dye-polluted wastewater: Synthesis, mechanistic insights and future outlook

Water borne emerging pollutants represents a significant challenge confronting the modern society. As a result of excessive use of dyes and pigments by the textile and other industries, substantial amount of these toxic and recalcitrant substances are widely dispersed into the aquatic sources that may raise serious health issues to all life forms besides causing potential disruption to the ecosystem. Treatments of these hazardous and non-biodegradable organic contaminants in wastewater effluents have become a focal point for researchers dedicated to environmental remediation. Notably, Metal organic frameworks (MOFs) and their composites have been reported to be promising materials for tackling such challenges. This review is dedicated to provide a concise overview by consolidating the diverse beneficial attributes of Cu-BTC MOF rendering it as a versatile material with applications spanning diverse domains, focusing on the reactivity, the role of the metal ion and its recent potential for addressing the elimination of toxic textile dye wastes from the wastewater effluent. Furthermore, it also documents the underlying mechanistic pathway governing the degradation mechanism and the superior electron transport property of Cu ̶ BTC, besides painting in detail the existing limitations that hinder their applicability at an industrial platform. Moreover, a set of future research outlooks serving as a roadmap for exploring the potentiality of Cu ̶ BTC MOFs have also been presented.

Understanding the Mechanism for Adsorption of Pb(II) Ions by Cu-BTC Metal-Organic Frameworks.

With the growing population, industrialization, and agriculture, water contamination not only affects people but entire ecosystems. Metal-organic frameworks (MOFs), because of their large surface area and porosity, show great potential as adsorbents for removing pollutants, such as heavy metals, from contaminated water. The current research aims at examining copper (II) benzene-1,3,5-tricarboxylate (Cu-BTC) MOFs and understanding the mechanism for their adsorption of Pb(II) from aqueous solution. The Cu-BTC samples were characterized using FTIR and XRD, and their surface area and porosity were determined based on N2 adsorption isotherms. The concentration of Pb(II) in the solutions was measured using atomic absorption spectroscopy (AAS). Both kinetic and equilibrium adsorption data were collected and then analyzed using numerical models. The analyses led to the findings that the limiting steps in the adsorption of Pb(II) on Cu-BTC are (a) pore diffusion of Pb(II) and (b) the availability of the active sites on Cu-BTC MOFs. It was further revealed that the former step is more dominant in the adsorption of Pb(II) when the lead concentration is low. The latter step, which is directly proportional to the surface areas of the MOFs, affects the adsorption to a greater extent when the lead concentration is high. The results also show that adsorption of Pb(II) ions on Cu-BTC is mainly a multi-layer heterogeneous process.

Preparation of Cu-BTC MOF extrudates for CH4 separation from CH4/N2 gas mixture

Metal-Organic Frameworks (MOF) are promising materials for gas separation and storage. The shaping of MOFs is an essential step for their practical industrial application. In this work, Cu-BTC MOF extrudates (B-5, B-10, and B-15) were prepared by using 5, 10, and 15 wt% of carboxymethyl cellulose as a binder and well characterized by powder X-ray diffraction (PXRD), N2 adsorption-desorption at 77 K, FTIR, TGA, and Scanning Electron Microscopy (SEM). The equilibrium adsorption isotherms of CH4 and N2 with Cu-BTC extrudates were measured at 298, 313, and 328 K and up to 10 bar pressure and compared with zeolite 13X and 5A. The isotherm data of both adsorbates were fitted in Dual Site Langmuir equations, and adsorption selectivity of methane over nitrogen was predicted using Ideal Adsorbed Solution Theory (IAST) method for 20:80, 30:70, and 50:50 (mol%/mol%) CH4/N2 feed gas mixtures representing nitrogen bearing coal bed methane. The CH4/N2 selectivity of Cu-BTC extrudates B-5, B-10, and B-15 was higher than commercial zeolite 13X and 5A. For example, for the 20:80 CH4/N2 feed mixture, the CH4/N2 selectivity of Cu-BTC extrudates B-5, B-10, and B-15 was 3.21, 3.24, and 3.25, respectively, which are about 38 & 34% higher than zeolite 13X and 5A which makes them potential adsorbent for further dynamic studies for the said separation application.

Enhancement of formic acid production from carbon dioxide hydrogenation using metal-organic frameworks: Monte Carlo simulation study

Formic acid production from CO2 allows the reduction of carbon dioxide emissions while synthesizing a product with a wide range of applications. CO2 hydrogenation is challenging due to the cost of transition metal catalysts and the toxicity of the transition elements. In this work, the thermodynamic confinement effects of the metal–organic framework UiO-66 on the CO2 hydrogenation to formic acid were studied by force field-based molecular simulations. The confinement effects of UiO-66 and the metal–organic frameworks Cu-BTC, and IRMOF-1 were compared, to assess the impact of different pore size and metal centers on the production of HCOOH. Monte Carlo simulations in the grand-canonical ensemble were performed in the frameworks, using gas phase mole fractions of CO2, H2, and HCOOH at chemical equilibrium, obtained from Continuous Fractional Component Monte Carlo simulations in the Reaction Ensemble. The adsorption isobars of the components in metal–organic frameworks were computed at 298.15 – 800 K, 1 – 60 bar. The enhancement of HCOOH production due to preferential adsorption of HCOOH in metal–organic frameworks was calculated for all studied conditions. UiO-66, Cu-BTC, and IRMOF-1 affect CO2 hydrogenation reaction, shifting the thermodynamical equilibrium toward HCOOH formation. The prevailing factor is the type of metal center in the metal–organic framework. The confinement effect of Cu-BTC turns out to exceed the enhancement caused by UiO-66, and IRMOF-1. The resulting mole fraction of HCOOH increased by ca. 2000 times compared to the gas phase at 298.15 K, 60 bar. Cu-BTC can be considered as an alternative to improve the production of HCOOH due to elimination of the high-cost temperature elevation, cost reduction of downstream processing methods, and comparable final concentration of HCOOH to the reported concentrations of formate obtained using transition metal catalysts.

Catalytic activity of Cu-BTC metal organic framework for borrowing hydrogen and tandem reactions of an alcohol under solvent and base free condition

The Cu-BTC (copper(II)-benzene-1,3,5-tricarboxylate) metal–organic framework was found to be a potential, stable and reusable catalyst for the solvent- and base-free borrowing hydrogen and tandem reactions of an alcohol. The Cu-BTC exhibited borrowing hydrogen activity in N-alkylation of aniline with benzyl alcohol, a model reaction of borrowing hydrogen, giving the saturated product (N-alkylated aniline). However, the formation of unsaturated product (chalcone) in the reaction of acetophenone with benzyl alcohol for α-C-alkylation, another model reaction of borrowing hydrogen, showed potential of Cu-BTC for the catalysis of tandem reactions to synthesize unsaturated products utilizing alcohols as a reagent. The study shows that the Cu-O pair sites of Cu-BTC are involved in the catalysis of borrowing hydrogen and tandem reactions.

Silver Ion-Exchanged Anionic Metal–Organic Frameworks for Iodine Adsorption: Silver Species Evolution from Ions to Nanoparticles

Ag clusters and nanoparticles have attracted much attention in the fields of environmental catalysis and pollutant removal. It is a common strategy to fabricate highly dispersed Ag nanoparticles in porous scaffolds via in situ growth. Here, anionic metal–organic frameworks (MOFs) have been employed to provide robust supports for Ag species. Ag nanoparticles with well-defined sizes are observed in MOFs when internal NH2Me2+ is exchanged with extrinsic Ag+ ions. The extended X-ray absorption fine structure and X-ray photoelectron spectroscopy spectra confirm that about 20% of Ag+ are reduced into Ag0, while the rest 80% are still Ag+ species. The comparison of Ag loading into anionic and neutral Cu-BTC MOFs suggests that the exchangeable cations facilitate Ag+ migration into the interior of MOFs and thus alleviate its aggregation and spontaneous reduction. Besides, the adsorption tests verify that all the Ag species in MOFs are accessible to iodine vapor to form AgI. The charge transfer from frameworks to trapped iodine and the water in the air promote the formation of iodide ions, which react with Ag+ to produce AgI. The iodine adsorption performance of MOF beads was also evaluated using the pore diffusion model. This work provides insights into the evolution of Ag species in MOFs and potential Ag-based adsorbents for radioiodine capture.

CuBTC metal organic framework-based dispersive solid phase extraction of cyclosporine and tacrolimus from plasma samples prior to determination by high performance liquid chromatography-tandem mass spectrometry

Immunosuppressive drugs are prescribed to reduce the immune system of persons who are undergoing organ transplants. The concentration of these drugs in blood and plasma samples must be accurately and precisely determined during immunosuppressive therapy due to their significant side effects. In this study, a metal organic framework-based dispersive solid phase extraction method was developed for the extraction of tacrolimus and cyclosporine from plasma samples before their determination by high performance liquid chromatography-tandem mass spectrometry. For this purpose, CuBTC metal organic framework nanoparticles were prepared by a hydrothermal approach and they were used as the sorbent in the extraction procedure. The adsorbed analytes were eluted by a suitable organic solvent and then more concentrated by evaporation of the eluate. All of the effective parameters of the method including sorbent amount, adsorption time, eluent type, desorption time, eluent volume, and sample solution pH were studied and optimized. They were obtained 5 mg, 5 min, acetone, 5 min, 300 μL, and 5, respectively. Under optimal conditions, the developed method was validated and the data showed that the linear range, the limit of detection, the limit of quantification, the coefficient of determination, the enrichment factor, and relative standard deviation values were 1–1000 ng mL−1, 0.30 ng mL−1, 0.5 ng mL−1, 0.99, 15.6, and 5.8 % for tacrolimus and 0.8–500 ng mL−1, 0.25 ng mL−1, 0.4 ng mL−1, 0.99, 17, and 5.6 % for cyclosporine, respectively. Finally, the method was successfully used in the determination of the studied drugs in plasma samples.

Epitaxial Single-Domain Cu-BTC Metal-Organic Framework Thin Films and Foils by Electrochemical Conversion of Cuprous Oxide.

Metal-organic frameworks (MOFs) are an important class of crystalline porous materials with extensive chemical and structural merits. However, the fabrication of MOF thin films oriented along all crystallographic axes to achieve well-aligned nanopores and nanochannels with uniform apertures remains a challenge. Here, we achieved highly crystalline single-domain MOF thin films with the [111] out-of-plane orientation by electrochemical conversion of cuprous oxide. Copper(II)-benzene-1,3,5-tricarboxylate, Cu3(BTC)2 (referred to as Cu-BTC), is a well-known metal-organic open framework material with a cubic crystal system. Epitaxial Cu-BTC(111) thin films were manufactured by electrochemical oxidation of Cu2O(111) films electrodeposited on single-crystal Au(111). The Cu-BTC(111) shows an in-plane antiparallel relationship with the precursor Cu2O(111) with a -0.91% coincidence site lattice mismatch. A plausible mechanism was proposed for the electrochemical conversion of Cu2O into Cu-BTC, indicating formation of intermediate CuO, growth of Cu-BTC islands, and termination with coalesce into a dense film with a limiting thickness of about 740 nm. The Faradaic efficiency for the electrochemical conversion was 63%. In addition, epitaxial Cu-BTC(111) foils were fabricated by epitaxial lift-off following the electrochemical etching of residual Cu2O underneath the Cu-BTC. It was also demonstrated that Cu-BTC(111) films with two in-plane domains and textured Cu-BTC(111) films can be achieved on a large scale using electrodeposited Au/Si and Au-coated glass as low-cost substrates.